I cant get into my laptop

Hey,

so, here's the story. My(annoying)little brother got a hold of my laptop when i was out and he's put a password on it and i can't get into it now. I switch it on and then this black screen with the word password comes up and he can't remember the password now!(i think he's lying) I really don't want to open my laptop up and take the (internal)battery out to fix it or take it to the shop to get it fixed, is there another/easy way of fixing this so i can use my laptop as normal again?
thanks
H
xx